1. Field of the Invention
The invention relates to a device for feeding curtain hooks, which each consist of a strip and a hook part connected thereto, to a sewing machine which can sew the strip of a supplied curtain hook to a curtain, comprising: a supply holder for the curtain hooks, displacing means for displacing one curtain hook at a time in a straight line to a desired position for sewing on the strip, and adjusting means for automatically adjusting the mutual position of strip and hook part connected thereto. The invention also relates to a method for feeding curtain hooks, which each consist of a strip and a hook part connected thereto, to a sewing machine which can sew the strip of a supplied curtain hook to a curtain.
2. Description of the Prior Art
The automatic feed of curtain hooks to a sewing machine along a straight path of movement is known from among others EP 0 637 345. Adjustment of the hook height, i.e. the mutual adjustment of a curtain hook consisting of a strip and a hook part, during the infeed route is also known from this publication. The use of the described device is particularly advantageous because it results in a reduced work load during the sewing of curtain hooks into curtains. Drawbacks of the prior art are that the existing devices take up a relatively large amount of space and that they function less precisely, particularly the hook height adjustment not being fully controllable.
The object of the present invention is to provide an improved device and method for automatic height-adjustment and feed of curtain hooks, whereby the drawbacks of the prior art are obviated while the existing advantages are retained.
The invention provides for this purpose a device of the type stated in the preamble characterized in that the adjusting means transport a curtain hook in a circle segment-shaped path from a position close to the underside of the supply holder to the straight line in which the displacing means displace a curtain hook, and during the progression through this circle segment-shaped transport path the desired mutual position of hook part and strip is adjusted. The displacement of the curtain hooks by means of a circle segment-shaped path prior to displacement thereof in a straight line to the sewing machine has a number of advantages. There thus results a greater freedom of choice in respect of the placing of the supply holder for curtain hooks; this no longer has to be localized above the linear feed path to the sewing machine. Particularly in the usually full curtain workshops in which the curtains to be manufactured require much space, this results in a considerable improvement in the utilization of the available space. The linear feed to the sewing machine can also take a more compact form. These feed means, heretofore often protruding in inconvenient manner, can be given a more compact embodiment.
Another advantage of the device according to the invention is that the first part of the infeed route (circle segment-shaped path), including the hook height adjustment, is hereby separated from the second part of the infeed route (linear path). This implies that, while the displacing means for displacing curtain hooks along a straight line are in operation, a subsequent curtain hook can already pass through the circle segment-shaped transport path, wherein it is simultaneously height-adjusted. The first part of the transport, including the hook height adjustment, hereby need not form part of the critical path in the feed and adjustment of curtain hooks. The device according to the invention can hereby operate more rapidly so that productivity can increase. A further advantage of adjusting the hook height outside the linear transport path to the sewing machine is that this enables a more certain locking of the strip of the curtain hook, whereby the adjustment of the position of the hook part on the strip can also be more readily controlled.
In a preferred embodiment the supply holder consists of a vertical tube in which the curtain hooks are buffered stacked on top of one another. Such a buffering of hooks is already known and can also be applied in combination with the device according to the invention. This enables the interchange of already existing supply holders with the device according to the invention. The advantage of the invention is that the relatively bulky supply holders can be placed at a position which is optimal for a seamstress, so that a holder is not inconvenient during use of the device and filling or exchanging of a supply holder is also simple.
In another preferred embodiment of the device the circle segment-shaped path of the adjusting means ends in or close to the straight line in which the displacing means displace a curtain hook. The circle segment-shaped path and the linear transport paths thus connect onto each other and no additional transfer means are required.
In yet another preferred embodiment the adjusting means comprise: at least one rotatable disc, which disc is adapted to carry a curtain hook, and a stop co-acting with the disc for engaging on the hook part of the curtain hook during rotation of the rotatable disc. Such a disc can be provided with locking means for fixing the position of the strip of a curtain hook carried by the disc. In order to obtain the desired hook height adjustment, an extreme working position of the stop can be adjustable, for instance by means of an adjusting member adjustable in a plurality of positions. Such adjusting means are relatively simple to manufacture and reliable in use. When a transmission is arranged between the adjusting member and the stop with a transmission ratio from a displacement of the adjusting member to a displacement of the stop for adjusting the extreme working position which is less than 1, it is then possible to adjust the device with an increased accuracy. Dimensional tolerances occurring during manufacture of the device or as a result of wear can thus be reduced (for instance by means of regular repeated fine adjustment of the device). The transmission ratio enables a precise control of the stop, with the resulting consequence that the hook height adjustment can be extra-accurate.
The adjusting means individually as described above also form part of the device according to the invention.
The invention moreover provides a method of the type stated in the preamble, comprising the successive steps of: A feeding a curtain hook from a supply holder along a circle segment-shaped path, a desired mutual position of the strip and the hook part being adjusted during the progression through this circle segment-shaped path, and B further displacing the curtain hook with adjusted hook height to a sewing machine along a linear path connecting onto the circle segment-shaped path. In a preferred application of this method the desired mutual position of the strip and the hook part is determined prior to progressing through step A by adjusting the means for feeding curtain hooks along the circle segment-shaped path. The orientation of the curtain hook after progressing through step A is preferably also the same as the orientation in which the curtain hook is further displaced according to step B. The advantages of this method are already described above with reference to the device according to the invention and the preferred embodiments thereof.